CONFIGURING IP SLA OVER HSRP

In this article I'll help you configure and test HSRP (Hot Standby Router Protocol) for a small campus network to ensure the recovery of user traffic transparently and immediately from first hop router failures.

Create a topology like shown below:

Configure the IP addresses on R1, R2 and R3. Then configure the virtual IP address 192.168.10.254 /24 and priority for the router using the commands given below.

R1:

R1(config)#int gi 0/0

R1(config-if)#standby ip 192.168.10.254

R1(config-if)#standby preempt

R1(config-if)#standby priority 110

R1(config-if)#standby track 1 decrement 20

R1(config-if)#ex

Now, configure the same IP address on R2’s interface.

R2:

R2(config)#int gi 0/0

R2(config-if)#standby ip 192.168.10.254

R2(config-if)#standby preempt

R2(config-if)#exit

Use the command ‘show standby’ in the enable mode to check the details.

We can observe that R1 is the active router because of the priority we set while configuring the HSRP.

Configure DHCP pool on R1 and R2 with the default gateway as 192.168.10.254 and R3 with 192.168.30.3

Now, the next step is to configure routing on the devices. I am configuring EIGRP 1 here.

R1:

R1(config)#router eigrp 1

R1(config-router)#no auto-summary

R1(config-router)#network 192.168.10.0

R1(config-router)#network 192.168.20.0

R1(config-router)#ex

R2:

R2(config)#router eigrp 1

R2(config-router)#no auto-summary

R2(config-router)#network 192.168.10.0

R2(config-router)#network 192.168.20.0

R2(config-router)#ex

R3:

R3(config)#router eigrp 1

R3(config-router)#no auto-summary

R3(config-router)#network 192.168.20.0

R3(config-router)#network 192.168.30.0

R3(config-router)#ex

Now, we will create the SLA to keep a check on the reachability to destination 192.168.30.3 from source R1.

R1(config)#ip sla 1

R1(config-ip-sla)#icmp-echo 192.168.30.3

R1(config-ip-sla-echo)#frequency 10

R1(config-ip-sla-echo)#exit

R1(config)#ip sla schedule 1 start-time now life forever

Now, let’s bind the IP SLA with the HSRP.

R1(config)#track 1 ip sla 1 reachability

You can use the command ‘show ip sla statistics’ in the enable mode to look into the details and verify the working of SLA after this by shutting the Gi0/1 interface of the Active Router. You will observer IP SLA failing, making the standby router active.